As follows from the observed mass composition a clear identification of individual sources would be difficult. This goal requires a thorough theoretical modelling of the effects of galactic and extragalactic magnetic fields on UHECR propagation and a shower-by-shower determination of the mass and energy of the primary particle.
The study of UHECR has an impact also in fundamental physics, as it involves tests of models and theories that extend beyond the standard model of particle physics. This is the case of SHDM that, being a viable alternative to the WIMP paradigm for DM, can be tested only through the observations of UHECR eventually connected with those of cosmology [1]}, [2]}, as follows from the right panel of figure REF .
